pyrolusite

a common mineral, manganese dioxide, MnO 2 , the principal ore of manganese, used in various manufactures, as a decolorizer of brown or green tints in glass, and as a depolarizer in dry-cell batteries.

pyrolusite

/ˌpaɪrəʊˈluːsaɪt/

noun

1.

a blackish fibrous or soft powdery mineral consisting of manganese dioxide in tetragonal crystalline form. It occurs in association with other manganese ores and is an important source of manganese. Formula: MnO2

Word Origin

C19: from pyro- + Greek lousis a washing +-ite1, from its use in purifying glass

"manganese dioxide," 1828, the name given in Roman times, when it was used, in a heated state, to de-colorize glass, from Greek elements pyro- "by heat, by fire" (see pyro-) + lysis "a loosening" (see lose).